The present invention relates to an electrical connector and, more particularly, to a connector specifically configured for permanent attachment to a medical electrode, such as an electrosurgical ground electrode.
In electrosurgical procedures, an electrical generator produces a high frequency electrical current which is applied to an active electrode. The active electrode may be configured as a scalpel which is used to cut tissue. The electric current causes coagulation at the incision, reducing bleeding. An indifferent or ground electrode, typically a single-use, disposable item, is attached to the patient and provides a return path to the generator for the high frequency current. The current supplied to the active electrode is concentrated in a relatively small area and high current densities are therefore obtained at the surgical site. It is essential, however, that the indifferent electrode provide for the current return to the generator over a relatively large surface area to maintain a low current density and thereby avoid injury to the tissue of the patient in this area.
It will be appreciated that it is of great importance that the current return path through the ground electrode to the electrosurgical generator remain unimpaired. If this current path should be interrupted, the electrosurgical current will be diverted to such alternate ground paths as may be available, such as for example, EKG electrodes attached to the patient or other grounded equipment in the operating room which may come into contact with the patient. Due to the much smaller surface area typically presented by such alternate ground paths, it is possible that the patient will be burned at the point where the current exits the patient's body.
It will be appreciated that not only must the ground electrode remain securely attached to the patient during the surgical procedure, but also the lead or leads from the electrosurgical generator must be securely connected to the ground electrode by an appropriate connector. In some cases, prior art disposable electrodes have been provided with a connection stud or tab to which a connector of a reusable lead assembly is attached. Connector arrangements for reusable lead assemblies are shown, for example, in U.S. Pat. Nos. 3,699,968, issued Oct. 24, 1972, to Bolduc; 3,842,394, issued Oct. 15, 1974, to Bolduc; 4,166,465, issued Sept. 4, 1979, to Esty et al; and 4,550,961, issued Nov. 5, 1985, to Aicher et al. Such a reusable lead assembly is economical since its cost is spread over many surgical procedures. Leads may, however, gradually deteriorate over time as a result of repeated folding and bending. If a lead assembly is not carefully checked on a routine periodic basis, the danger exists that a damaged lead might go unnoticed. Additionally, since the connector for such a lead assembly is specifically designed to be connected to and removed from numerous electrodes, the possibility of accidental disconnection of the connector from the electrode exists.
Other types of disposable ground electrodes have, in the past, been provided with a lead assembly which is permanently attached to the electrode, and discarded with the electrode after the completion of the surgical procedure. Such electrodes, although more expensive, are advantageous in that no periodic inspection and maintenance program is required for the electrode leads, since a new set of leadsd is used on each surgical procedure. Additionally, since the lead assembly is intended to remain permanently attached to such an electrode, the connector may be designed to limit the likelihood of inadvertent detachment of the leads from the electrode. Further, such electrodes eliminate the need to sterilize leads after each surgical procedure.
A number of different, permanent lead connection arrangements have been utilized. Typically, a layer of foil or metallized plastic in an electrode is in electrical contact with a layer of electrically conductive gel held against the patient's skin or is coupled capacitively to the patient's skin by means of an overlying sheet of dielectric material. The lead ends may be attached to the foil sheet by means of crimp elements which engage the lead wire ends, the foil sheet, and perhaps other layers of foam material in the electrode. Alternatively, a metal stud, extending through the foil layer, may have a lead wire attached by a ring type terminal crimped therearound. As yet another alternative, the foil layer may define a tab against which lead terminals are secured by a covering layer of adhesive coated foam.
It is desirable to provide a connector for permanent attachment of conductor leads to a medical electrode in which the electrode is positively engaged, in which lead terminals on the ends of the lead wires are securely held in electrical contact with an electrically conductive layer of the electrode, and in which a strain relief for the leads is provided to reduce strain on the connector when a force is applied to the leads.